Just some walking animation glitches with the freecam.
I don't think that this can be done with a keyboard.
Video
Heh,awesome.And it's possible on a keyboard,I just tested it right now and i laughed out loud.
Edit: I just found out that you can also run in slomo if you Run,freecam,pause the game then unpause holding the walk button.
And if you hop and hit the ground,freecam and pause before the ground impact animation is done,holding the Walk or Run button when you unpause will make the animation to freeze.